As the Internet becomes increasingly popular, a new paradigm is being developed in networked computing known as nomadic computing or mobile computing. Mobile computing aims to provide a network infrastructure and corresponding terminal capability to perform all desktop-like computing functions seamlessly at any place or time, even while the terminal is moving. This means that anytime and anywhere, a user would be able to browse the web, check e-mail, play digital music, and perform all other computing activities without having to be behind a desktop at home or work. At its best, mobile computing would allow a user to have access to a consistent working environment.
Practically, mobile computing is a challenge for several reasons. For anytime, anywhere functionality, the user must be able to carry the mobile computing device. The computing device must be small, light, and at the same time be capable of performing the complex tasks of a desktop computer. Anytime, anywhere access to a network will also require wireless connectivity as the user cannot be tied to a place where a wired connection is available. Both of these requirements are quite challenging to fulfill.
Currently, small lightweight devices operating on battery power are resource constrained. The display cannot be large, bright, or complex as this affects size and power consumption. For the same reason, the processing power, memory, storage space, and communication ports are limited or non-existent. Ideally, mobile computing devices would be dumb terminals with all the services and computation performed by a powerful server computer on a network. In such a scenario, the mobile computing device would simply be a display for the information transferred from the server. However, current wireless connectivity is neither ubiquitous nor uniform. Data rates on wireless connections can range between 9.6 kbps in outdoor areas with wide coverage to 11 mbps in indoor areas with local coverage. This means that a user may not be always connected, and if the user is connected, the connections could be very slow or quite fast.
One solution to the problem of dynamic connection quality and disconnections is for the mobile computing device to download the information when there is good connectivity and then be able to work offline. The mobile computer must be sophisticated enough to store the information and process it offline. However, this approach is contradictory to the requirement that mobile computing devices be simple and dumb. As the flow of information is over wireless connections, security also becomes an issue and is especially challenging due to the size and resources of the device. There is consequently a tradeoff between the form factor of the device and the ability of the device to provide the user with a rich set of services.
Advances in technology have reduced many of these limitations, and mobile computing is closer to reality than ever before. Mobile computing devices are becoming smaller, lighter, and more powerful than their predecessors. They also come in various types and connectivity options. Two prominent classes of mobile computing devices today are those that use the PalmOS and the PocketPC operating systems. The former class of devices holds a dominant share of the market whereas the latter is growing in market size and is especially popular with executives in business organizations. Often referred to as palmtop computers or handheld computers, these devices are capable of simple word processing, spreadsheet applications, web browsing, calendar notations, and address management. There are low-end handheld computers with monochromatic displays, low resolution, limited memory, and somewhat bulky sizes. Higher-end devices are extremely thin, have a high-resolution, and can include color displays.
Because the size of handheld computers is expected to be small, but they are required to perform many tasks, manufacturers have adopted an "expansion slot" approach. Essentially, a handheld computer is equipped with a slot where a variety of attachments can be connected. Attachments could include memory cards for storage, a Global Positioning System (GPS) receiver for determining the user's location, a digital camera, an MP3 player for digital music, or modules for network connectivity—wired or wireless. Some of the attachments have their own power supply, increasing the size/weight of the handheld computer, but because they can be used only when needed, it eliminates the necessity of having all capabilities available in the handheld computer at the same time. The expansion slots of one device may not match that of a device from another vendor. For example, PocketPC devices have standard Type II PC card slots or flash card slots. But PalmOS devices have different slots like the larger Springboard module or postage stamp-sized secure digital/multimedia card slots.
Wireless connectivity for handheld computers also comes in several varieties. Most handheld computers come with built-in infrared ports that can be used to exchange information with a network or another computer at short range. Many of them can connect to wireless local area networks (LANs) based on the IEEE 802.11 standard. They can also connect to wireless services like Mobitex and the cellular digital packet data (CDPD) networks that provide service over larger areas spanning cities and along highways, although at a lower data rate. Some cellular telephone service providers are also making cell phone modules available for attachment to the expansion slots of handhelds computers. Bluetooth, a new wireless standard for personal area networking , is also available for some handheld computers.
Recently, the free Linux operating system has been modified to run on handheld computers of different types. Some manufacturers are also adopting Linux for their handheld computers. As this operating system carries no licensing fee, it could further reduce the cost of handheld computers. In developing countries like India, voice activated Linux-based simputers have been developed for mass usage in rural areas where the computing infrastructure is limited. Device integration, such as the integration of cell phones and handheld computers, is also occurring. Location aware mobile computing—in which a person is able to obtain information on local restaurants, theaters, coffee-shops, maps, driving directions, traffic, weather, news, tourist attractions, and the like on a handheld computer—is also becoming prominent.
see also Embedded Technology (Ubiquitous Computing); Geographic Information Systems; Wireless Technology.
Dhawan, Chander. Mobile Computing: A Systems Integrator's Handbook. New York: Mc-Graw-Hill, 1997.
Roth, Cliff. Mobile Computing for Dummies. Foster City, CA: IDG Books, 1997.